Food cover for providing both closed and full open positions and including side panels, an off-site mountable hinge and mirror image front and back panels
FIELD OF THE INVENTION 
     The present invention relates to food covers. More particularly, it relates to the design, formation and use of such covers in order to provide both a full closed working position and an open position relative to a food tray or the like. 
     RELATED APPLICATION 
     In my copending application, Ser. No. 07/467805, filed Jan. 19, 1990 entitled &#34;FOOD COVER FOR PROVIDING BOTH A FULL CLOSED POSITION AND A QUASI-OPEN, SNEEZE GUARD POSITION AND INCLUDING SIDE PANELS, A SEGMENTED HINGE AND MIRROR IMAGE FRONT AND BACK PANELS&#34; and incorporated herein by reference, there is disclosed an embodiment for a food cover that includes a pair of mirror imaged, front and back panels swingable hinged to upright side panels via a central lateral support. In the aforementioned design, the side panels are integrally linked across opposite upper segments to the lateral support. 
     In many applications, as where the food cover is to be used off site on a temporary basis, such a subassembly can be awkward to transport, especially where other equipment in addition to the food is to be delivered at the same time to the off site location. 
     BACKGROUND OF THE INVENTION 
     There has been an increased need to provide efficient food catering services for off-site occasions such as wedding, birthday and garden parties and the like. For such parties, the caterer provides not only the specialty foods, but also all the equipment to serve such foods including food covers, trays, tables, utensils, etc. In transporting such gear to the off-site location, the caterer must carefully stow these items as separate stackable units since available space in his van, truck or the like is limited. 
     At the off-site locations, the food trays are each provided with separate food covers. One such design I am familiar with uses two domes hinged together by a metal piano hinge across their tops. 
     The design has several drawbacks. The piano hinge is attached by rivets or the like. Hence once assembled, disassembly of the cover for whatever purpose and re-assembly, is impossible without extensive modification of the design. Hence such covers cannot be easily disassembled and re-assembled at the off site location. 
     While the prior art is replete with food covers, I am unaware of any design having the following advantages, in combination: 
     (i) that can be assebled from separate molded plastic elements at the off-site use location without tools; 
     (ii) after assembly at the off-site location, that can provide protection of food both in a full closed position yet be easily opened to a full open position to serve or to replenish the food; 
     In this regard, I have reviewed U.S. Pat. Nos. 1,080,551; 2,770,389 and 4,723,693 which show split lid designs for ice chests, frying pans, shakers and the like. These covers have open positions that either are overcenter from any vertical plane through the hinge, or that vary as a function of thickness and type of plastic used to form the hinge. U.S. Pat. Nos. 1,745,548; 3,015,405; 4,005,798; 4,773,555 and RE 32,745 are likewise distinguishable in that for the most part, overcenter open positions attained by mechanical linkages are taught. An exception is U.S. Pat. No. 4,005,798 where the user physically lifts the cover from the pan and uses a slotted metal block attached to the side of the cover to position the cover in an almost vertical position. 
     SUMMARY OF THE INVENTION 
     In a preferred form, the present invention includes a pair of upright side panels resting upon a substantially horizontal base such as a table or the like, and a pair of mirror image front and back L-shaped panels. 
     The side panels each has a pair of oppositely canted, support stops molded in its side wall. Each stop is equi-spaced about a working plane normal to both side panels and the horizontal base. 
     Each L-shaped front (or back) panel includes an upright, wall segment having forward (or rearward) edges that rests upon the horizontal base in the closed position of the food cover, and a roof segment that is canted about a plastic spider hinge coincident with the working plane. The roof segments are designed to be oppositely canted about the hinge but match the respective cants of the support stops of the upright side panels. In both the full closed and half-open positions of the food cover, the roof segments are directly supported by the canted support stops of the side panels. That is, since the canted regions of the L-shaped panels are mirror imaged, as one is rotated and the other is stationary, eventually a stable nesting position is established between the two regions. As the canted roof segments nest together one atop the other, support for the new loading relationship shifts from all four support stops of the side panels (when both front and rear L-shaped panels were in the closed position) to one in which both panels are supported by the support stops of the stationary L-shaped panel. 
     The spider hinge also includes a central spine segment coincident with the pivot axis and a plurality of arms and legs radiating from the spine segment, two of which attach to the roof segment of each L-shaped panel by means of a series of hand tightened wing nut-bolt combinations. Thus, the invention can be easily assembled and disassembled at an off-site location without tools. 
     The orientation and design of the L-shaped panels (with their complementary roof cants) and the shape of the spider hinge, permit the L-shaped panels to be separately swingable about the working plane coincident with the pivot axis. Yet both L-shaped panels can also be strongly locked in both the full closed and open positions relative to the horizontal base surface. 
     Assembly at the off-site location includes attaching the spider hinge to the L-shaped panels by inserting the wing nut bolt combinations through aligned openings in the legs of the hinge and in the lips of the roof segments of the L-shaped panels. The wing nuts are then hand tightened. After the front and rear panels are attached, they are placed over the side panels resting on the four support stops. Thus the closed position of the food cover about a tray of food and the like is easily established. To open the food cover, since the panels have opposite cants to their respective roof segments, as one is rotated and the other is stationary, eventually a stable nesting position is established between the two regions. As the canted roof segments nest together one atop the other, support for the new loading relationship shifts from all four support stops of the side panels (when both front and rear L-shaped panels were in the closed position) to one in which both panels are supported by the support stops of the stationary L-shaped panel. 
     Disassembly is the reverse of the above steps. All disassembly steps, of course, occur without the need for tools. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of the food cover of the present invention illustrating a spider hinge, a pair of side panels and front and back L-shaped panels; 
     FIGS. 2 and 3 are plan and side views, respectively, of the food cover of FIG. 1; 
     FIG. 4 is an perspective view of the food cover of FIG. 1 partially exploded to illustrate the construction of the side panel in more detail, with the remaining side panels being omitted; 
     FIG. 5 is enlarged detail of one of the L-shaped panels of FIG. 4; 
     FIG. 6 is a section taken along line 6-6 of FIG. 2; 
     FIG. 7 is an enlarged detail of the spider hinge of FIG. 6. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a plan view of an food cover 10 of the present invention. The cover 10 includes separately molded, upright side panels 11 and 12, and L-shaped front and back panels 13 and 14. As shown in FIGS. 1, 2 and 3, the cover 10 is in contact with a horizontal base such as table top 16. 
     The panels 11-14 are preferably formed by first injecting and curing plastics material within a mold. Each panel 11-14 is composed of the following: side panels 11, 12 are duplicates of each other and each includes a side wall 17 terminating in exterior and interior upright surfaces 18, 19 (FIG. 2) and four, separate support stops 20a-20d extending from the interior surface 19 toward the center of the cover 10. The pairs of stops 20a, 20b (of side panel 11) and 20c, 20d (of panel 12) are each separated by a similar distance D1, see FIGS. 1, 3, 4 and 6. 
     Note also that the matched support stops 20a, 20b and 20c, 20d of each upright side panel 11, 12 are oppositely canted with respect to working plane P while lateral pairs of stops (viz., stops 20a, 20c and 20b, 20c) are similarly canted. Thus in either closed or open position of the food cover 10, there is sufficient rigidity to assure stability. That is, in closed position, the weight of the front and back panels 13, 14 is distributed the matched support stops 20a-20d and the bottom edges 15 of the front and back panels 13, 14. However, in the open position for either of the front and back panels 13, 14 the following positioning results: the weight of the opened panel 13 or 14 is distributed between the lateral stop pairs 20b, 20d or 20a, 20c and the bottom edges 15 of the stationary panel 13 or 14. That is, in the closed position, front panel 13 rests on lateral pair of support stops 20a, 20c , while back panel 14 rests on lateral pair 20b, 20d. Hence, both positions are stable. 
     As shown in FIGS. 1 and 3, the working plane P is normal to both the base 16 and the upright surfaces 18, 19 of the side panels 11, 12. 
     As shown in FIG. 4, the front and back L-shaped panels 13, 14 are each of unitary mirror image design and can be formed also using a mold. Since the panels 13, 14 are mirror images of one another, a description of one suffices for the other. 
     Each panel 13, 14 comprises an upright segment 21, a horizontal mid-roof segment 22 and a canted end-roof segment 23 terminating in lip 28. Note that canted end-roof segment 23 of front panel 13 rests on the stop 20a of side panel 11, while the oppositely canted end-roof segment 23 of the back panel 14 rests on stop 20b of the same panel 11. Between the upper end of upright segment 21 and roof segments 22 and 23 is a pair of triangularly shaped ribs 25 associated with each panel 13 or 14. The ribs 25 strengthen the panels 13, 14 and prevent wobble as the panels 13 or 14 are pivoted by means of spider hinge 30 in the manner explained below. A single axis of rotation for the panels 13, 14 is shown at 31. 
     As shown in FIG. 5, at the bottom end of the upright segment 21 of each panel 13 or 14, is formed terminating edge 15 previously mentioned. It is slightly flared over region 26a and includes a rubber bumper 26b. 
     Returning to FIG. 4, the mid- and end-roof segments 22, 23 are seen to meet at 27. While the intersection of the end-roof segment 23 with the lip 28 forms an angle θ. A handle 29 is attached to the vertical segment 21 of each panel 13, 14 as by screws, not shown. 
     FIGS. 3 and 6 illustrate that the front and back panels 13, 14 are swingable relative to the side panel 12 via spider hinge 30 in the manner explained below. A singe axis of rotation is shown at 31 of the hinge 30 coincident with the working plane P. 
     Pivot action occurs by swinging the panels 13, 14 upwardly from the table top 16 about axis of rotation 31. As shown in FIG. 3, the panels 13, 14 protect flat food tray 32 and pastries 33 shown in phantom line. 
     In FIG. 3, the two operating positions of the panels 13, 14 are shown. The closed position is more clearly shown in solid line. The open position is shown in phantom line at numeral 34. In both the full closed and open positions of the food cover 10, the front and back panels 13, 14 are directly supported by the canted support stops 20a-20d of the side panels 11, 12. That is, since the L-shaped panels 13, 14 are mirror imaged, as one is rotated and the other is stationary, eventually a stable nesting position is established between the two regions. As the canted roof segments nest together one atop the other, support for the new loading relationship shifts from all four support stops 20a-20d (when both front and rear L-shaped panels 13, 14 were in the closed position) to one in which both panels 13, 14 are supported by the support stops of the stationary L-shaped panel, viz., support stops 20b, 20d of back panel 14 in FIG. 3. 
     FIG. 7 illustrates plastic spider hinge 30 of the invention in more detail. 
     The hinge 30 is segmented and includes a pair of legs 42, 43 and a pair of arms 45, 46 that project from a central spine 44. Each leg 42, 43 is vertical and off-set a horizontal distance D2 from the other. Each is also rectangular in cross section. 
     As a result, the roof segments 22, 23 of the front and back L-shaped panels can be attached via lips 28 to the legs 42, 43 by wing nut-bolt combinations 46. The combinations 46 are designed to enter through openings 47 within both lips 28 and legs 42, 43 of the hinge 30. After attachment via wing nuts 48, bolt head 49 is seen to rest in the cavity 50 formed between the legs 42, 43 below the spine 44 of the hinge 30. 
     In accordance with the invention, the orientation and design of the roof segments 22, 23 of the L-shaped front and back panels and the shape of the spider hinge 30, permit either of these panels to be separately swingable about pivot axis 31 coincident with working plane P. Yet these panels 13, 14 can also be strongly locked in a full open position, as desired. 
     Since the complementary cants of the arms 45, 46 of the hinge 30 are mirrored in the similar orientation of both the end roof segment 23 and of the support stops 20a-20d, this design aids the user to correctly position the front and back panels during operations. That is, the canted design of the invention permits the user to easily attain one of two positions: (i) a closed position wherein both pairs of stops 20a, 20b and 20c, 20d are used to support the front and back panels at four locations; and (ii) in an open position in which the lateral pairs 20b, 20d or 20a, 20c support both panels 13, 14 in a nested relationship. 
     In more detail in FIG. 7, the rotation outline of the hinge 30 is seen to be within annular space 51 positioned between stops 20c, 20d, yet does not intersect the plane of the latter. i.e., during rotation about the pivot axis 31 to an open position, both the attached lips 28 and legs 42 and 43 easily clear the stops 20c, 20d since the diameter of rotation space 51 is less than the distance D1 between the stops 20c, 20d. 
     Attachment between each of the arms 45, 46 and legs 42, 43 of the hinge 30 with the front and back panels is defined by a rectangle having a lateral dimension equal to the length of the hinge 30 and transverse dimension equal to the length of arms 45, 46 or the length of the legs 42, 43. Such attachment is generally indicated at 52 and is seen to be associated with one of the following: (i) arms 45, 46 atop the canted end-roof segment 23 and (ii) legs 42, 43 in contact with lips 28. As to item (i), above, note also that such surface contact 52 is canted to the same degree as the cant of end-roof segment 23 and thus forms a firm anchor should it be stationary during rotation of the other panel from an original stable position (say FULL CLOSED-TO-OPEN or vice versa) to a new stable position. As to item (ii), above, the length of each leg 42, 43 and the lip 28 is less than the distance Di between the support stops 20c, 20d. The distance D1 is measured between near terminating edges 53 (relative to the working plane P) of the support stops 20c, 20d. When one of the panels is rotated about the pivot axis 31, the annular space 51 defines the edge of the pathway of rotation of the surface contact 52 between the leg 42 or 43 and lip 28 of the rotating panel. As previously mentioned, the pathway of rotation is seen to be clear from contact with and passes freely between the stops 20c-20d. 
     In FIG. 7, the canted stops 20c, 20d are also seen to define complementary skew angles θ1 and θ2 where θ2 is equal to 180-θ1, relative to a horizontal normal to the working plane P. Such angles θ1 and θ2 are each between 20 and 30 degrees. Hence the rotation angle is equal to 180-2(θ1). 
     Likewise, the arms 45, 46 of the hinge 30 are oppositely canted relative to each other in opposite complementary directions when the front and back panels 11, 12 are in closed positions. These complementary directions follow the contour of the end roof segments 23 as previously explained, and likewise are defined by the complementary skew angles θ1 and θ2 previously discussed. 
     Returning to FIG. 7, after the lips 28 of the end-roof segment 23 has been attached via wing nut-bolt combinations 46 to the hinge 30 in the closed positions, the unstressed position of the hinge 30 is attained. The hinge 30 is stressed when either of the panels 13 or 14 is rotated relative to pivot axis 31. But the hinge 30 has sufficient rigidity to keep the panels 13, 14 in correct working position. That is, the thickness of the spine 44 is sufficient to prevent collapse at the axis 31 during and after rotation. 
     METHOD ASPECTS 
     Assembly at the use site includes positioning elements of the hinge 30 in close proximity of the lips 42, 43 of the L-shaped panels 11, 12. Then these elements are attached using wing nuts 48 of the nut-bolt combinations 46. These wing nuts 48 are tightened relative to bolt head 49 by hand pressure. The front and back panels 13, 14 with hinge 30 attached are next placed in contact with the stops 20a-20d of the side panels 11, 12 to complete assembly. Disassembly is the reverse of the above steps. All such steps also occur without the need for tools. 
     Having described a method and apparatus in accordance with the invention in which advantages can be appreciated by those skilled in the art, it also is evident that certain variations are suggested. It is therefore my intent that such variations be within the scope of the invention as set forth in the following claims.